Many of today's A/V equipment have an optical audio output. Known as TOSLINK, it provides an alternative way of running audio into a receiver. It's especially handy if you need to use the HDMI output to one component like a TV and simply want to run audio to the receiver. The Axis TOSLINK Digital Optical Cable, 6 ft., is not affected by electrical interference the way wire cables can nor can it cause ground loops. It also keeps the signal in the digital domain for better quality. That's because it is fiber-optic and uses laser light to transmit the audio signals.